I'm trying this on the pitted stuff for a re-furb:
EVAP-O-RUST.
This.
Seriously, worth its weight in gold. Dunked a bunch of bolts and fittings overnight.
The only possible warning I can issue is this: With some types of chrome it'll give it a 'smoke' effect if left in for more than the recommended 12 hours, but it's easily polished out with any chrome cleaner or even Mothers mag & wheel polish.